Percentage profitable positions between 70 and 80

I have a strategy that does not include a stop loss
The percentage of profitable positions in a large part of symbols in the strategy is between 70 and 80 percent as you can see in the pictures
When I add stop loss settings the percentage of profitable positions drops to less than 50 percent.
The problem with some symbols is that even if the percentage of losing positions is only 30 percent, their loss is still greater than 70 percent of the winning positions, which causes the strategy to lose over time. As you can see in the EUR/CAD graph, 73 percent of positions are profitable and the strategy is still losing
How can I use the stop to stop the big losses of the losing positions but without damaging the winning positions.
I would love to hear ideas.

In my opinion the E/U has large uncertainties during news time, therefore maybe if there is no SL it will be a disaster. I am a newbie, but this is my idea. There have to be SL in news time, or when it face like NFP events it will suffer more than 100 pips lost.